histotrophically

Histotrophically describes a mode of embryonic nutrition found in some animal species. It refers to the process where the developing embryo receives nourishment from the mother's uterine tissue, specifically from uterine glands and the endometrium. This nutrient supply is often referred to as histotroph, which is derived from the Greek words "histos" meaning tissue and "trophos" meaning nourishment.

This form of embryonic development contrasts with other reproductive strategies such as oviparity (egg-laying with external yolk) or viviparity where the embryo receives nutrients directly from the mother's bloodstream via a placenta. In histotrophic species, there may be a less specialized or absent placental structure, and the embryo directly absorbs nutrients secreted or shed by the maternal endometrium. The exact mechanisms and composition of histotroph can vary significantly between species. This reproductive strategy is observed in certain species of sharks, bats, and marsupials, among others, and represents an evolutionary adaptation to provide sustained nourishment to developing young within the maternal body.